1. Field Of The Invention
This invention relates to methods and apparatus for performing block squeeze cementing jobs on oil wells, and more particularly, to a packer apparatus and method of use which eliminates one wireline trip and one tubing trip.
2. Description Of The Prior Art
It is sometimes desirable in production of oil wells to place cement through perforations in the casing of the well both below and above the oil producing formation or zone. This cementing is carried out to prevent water and/or gas from migrating to the wellbore along with the oil. The intent is to leave the water and gas in the formations adjacent to the oil producing zone so that the water and gas will drive the oil to the wellbore, thereby increasing recovery of oil.
Current procedures for accomplishing this comprise making a lower set of perforations and then squeezing cement into the zone below the oil producing zone. Typically used is a drillable squeeze packer, such as Halliburton's EZ Drill.RTM. SV Squeeze Packer, which is similar to that illustrated in U. S Pat. No. 4,151,875 to Sullaway, assigned to the assignee of the present invention. The packer is set above the lower set of perforations, and cement is squeezed into this lower perforated zone.
In this prior art procedure, a set of upper perforations is then made above the oil producing zone, and cement is squeezed into the formation above the oil producing zone using a retrievable packer, such as the Halliburton RTTS.RTM. Retrievable Packer.
This prior art process works well. However, making the upper and lower perforations and setting of the drillable packer are conducted on a wireline. The lower perforations are made first, and the drillable packer is set. Then, the wireline company personnel must remain at the location until the first cementing job is done before they can make the second set of perforations. The result is an additional wireline trip with increased expense in the entire block squeeze cementing job. Therefore, there is a need for a cementing job which can reduce the number of trips into the wellbore, and particularly one which does not require wireline company personnel waiting on other operations.
The present invention meets this need by providing an apparatus and method for block squeeze cementing which allows both sets of perforations to be made during one wireline trip into the well. The drillable packer is then set, and the wireline company personnel can leave. The present invention also eliminates one trip in the well with a well tubing string by permitting both squeeze cementing jobs to be done on the same tubing trip.